Geology and mineralazation in the southern Lachlan Fold Belt: A probable Mississippi Valley-type lead-zinc deposit at Cooleman Plains, southern New South Wales

Abstract

The Mount Black lead?zinc deposit at Cooleman Plains, southern New South Wales, occurs in the uppermost part of the moderately folded, weakly metamorphosed, Upper Silurian Cooleman Limestone. A joint controlled collapse-breccia zone interpreted as a palaeokarst structure has been partly replaced by quartz, sphalerite with a low to moderate Fe content, Ag-poor galena, and a little chalcopyrite, pyrite, marcasite, tetrahedrite, arsenopyrite and mackinawite. These minerals show evidence of having encrusted and replaced limestone fragments in the breccia. Oxidic Zn, Pb, Cu and Fe minerals have formed by the near-surface oxidation of the sulphides.